Rethinkdb: Including a subdocument for nested doc - rethinkdb

Question

I am performing an operation, and it works, but I want to know if there is a better or more efficient way to do what I want.
I have an object in my db that looks like this:
{
"id": "testId",
"name": "testName",
"products": [
{
"name": "product1"
"info": "sampleInfo",
"templateIds": [
"asdf-1",
"asdf-2"
]
},
{
"name": "product2"
"info": "sampleInfo",
"templateIds": [
"asdf-1",
"asdf-2"
]
}
]
}
As you can see, each "product" in the "products" array has a sub-array of templateIds. These match templates stored in another table. What I want to do is create a query that merges those templates onto each product object before I send it all back.
Currently I am doing this with sub-merges:
r.table('suites').get('testId').merge(function(suite){
return {
products: suite('products').merge(function(product){
return {
templates: r.expr(product('templateIds')).map(function(id) {
return r.table('templates').get(id)
})
}
})
}
})
My question is: is there a more efficient way to do this? Or is there a completely different way of thinking I should employ to do this?
Thanks guys!

Answer 1

That looks right to me. The only thing I can think of is that r.table('templates').get_all(r.args(product('templateIds'))) is shorter than product('templateIds').map(function(id){ return t.table('templates').get(id);}) and might well be faster.
EDIT: If you have a small number of templates, another thing that would make this run faster would be to do the substitution in the client instead and cache the retrieved templates by ID. RethinkDB will have to do a separate read for each template ID, even if it sees the same one over and over again, because it doesn't know enough to know whether or not caching those values is safe.